A singulation procedure is typically performed to separate integrated circuit packages such as IC chips from a substrate such as a circuit board. During singulation, the substrate is typically held in place while one or more saw blades cut straight lines through the substrate to form the individual integrated circuit packages. Although dicing with saw blades has worked well, continuing advancements in the industry have tested the limitations of saw singulation.
Cutting small devices is particularly problematic for saw singulation. When device dimensions are small as for example less than 3 mm×3 mm, vacuum fixtures are unable to retain the small devices during sawing, with consistency. As the saw blade passes through a device, it is both rotating and translating relative to the device under process. The resulting force vectors have both vertical and shear components. As the shear component overwhelms the holding force of the vacuum fixture, the singulation yield drops due to non-conforming geometries, damage, or lost parts. As feed rates increase, the magnitude of the shear component increases commensurately and magnifies the device retention problem. Therefore, feed rates are minimized to protect yields. The result, however, is lower throughput.
High consumable cost is also problematic for saw singulation. Saw singulation may require specially formulated blades that must constantly expose new diamonds to the cut interface. As the diamonds remove material, they are “dulled” by the materials used in the substrate and must be sloughed-off as the blade wears at a higher-than-normal rate. The balance between blade wear and cut quality is a delicate trade-off requiring costly technology to extend blade life while minimizing burrs and chips.
Curvilinear cutting paths are also problematic for saw singulation. Many new devices as for example photonic devices are produced with precise curved boundaries rather than straight edges. Curved boundaries require curvilinear cut paths, which saw blades do not readily accommodate. By definition, the cut path of a rotating blade must be the straight line defined by the intersection of the blade plane and the device plane. Saw singulation simply does not lend itself to curvilinear cutting paths as needed by these new devices.
Based on the foregoing, there is desired an improved apparatus and method of singulating a substrate into a plurality of component parts.